Method for identifying temperature changes, caused by a defect, at wheel ends of a vehicle, evaluation unit and vehicle

Abstract

A method is for identifying fault-induced temperature changes at wheel ends of a vehicle. At least two of the wheel ends have a wheel speed sensor having a temperature sensor configured to measure around its position a sensor temperature in a sensing region. The method includes: retrieving a first sensor temperature measured by a first temperature sensor at a first wheel end; and retrieving a second sensor temperature measured by a second temperature sensor at a second wheel end; determining a temperature deviation on the basis of the first sensor temperature and the second sensor temperature; comparing the temperature deviation with a deviation limit value; and outputting a notification when the deviation limit value is exceeded, which notification includes that a temperature change induced by a fault has been detected at least at one of the wheel ends that have a wheel speed sensor having a temperature sensor.

1 . A method for identifying fault-induced temperature changes at a plurality of wheel ends of a vehicle including a first wheel end and a second wheel end, wherein at each of the plurality of wheel ends a wheel is rotatably mounted, the first wheel end has a first wheel speed sensor for measuring a wheel speed of a first wheel and the second wheel end has a second wheel speed sensor for measuring a wheel speed of the first wheel, the first wheel speed sensor has a first temperature sensor configured to measure, around a position of the first temperature sensor, and to output a first sensor temperature in a first sensing region, which encompasses at least the first wheel speed sensor, the second wheel speed sensor has a second temperature sensor configured to measure, around a position of the second temperature sensor, and to output a second sensor temperature in a second sensing region, which encompasses at least the second wheel speed sensor, the method comprising:
 retrieving the first sensor temperature measured by the first temperature sensor of the first wheel speed sensor at the first wheel end;   retrieving the second sensor temperature measured by the second temperature sensor of the second wheel speed sensor at the second wheel end;   determining a temperature deviation on a basis of the first sensor temperature and the second sensor temperature;   comparing the temperature deviation with a deviation limit value; and,   outputting a notification if at least one of the deviation limit value is exceeded and the first sensor temperature and the second sensor temperature deviate too widely from each other, wherein the notification includes that a temperature change induced by a fault has been detected at least at one of the first wheel end and the second wheel end.   
     
     
         2 . The method of  claim 1 , wherein the notification includes that a friction-inducing fault that results in a temperature change in the sensing region of the associated temperature sensor has been detected at the wheel end that has the currently higher sensor temperature. 
     
     
         3 . The method of  claim 1 , wherein a specific deviation limit value is set for each fault. 
     
     
         4 . The method of  claim 1 , wherein each of the deviation limit values is set according to the position of the associated temperature sensor at least one of: at the associated wheel end and inside the associated wheel speed sensor. 
     
     
         5 . The method of  claim 1 , wherein the deviation limit value is adjusted adaptively during driving. 
     
     
         6 . The method of  claim 1 , wherein at each of the plurality of wheel ends is arranged a brake pad of a service brake, which, in order to brake an associated wheel, is configured to be pressed against a brake disk connected to the associated wheel, when a braking request is present. 
     
     
         7 . The method of  claim 6 , wherein the notification at least one of when the deviation limit value is exceeded and if the two sensor temperatures deviate too widely from each other includes that a first service brake, which is assigned to the first wheel end, or a second service brake, which is assigned to the second wheel end, according to which associated sensor temperature is higher, is overheating or has overheated as a result of a fault. 
     
     
         8 . The method of  claim 7 , wherein the fault is caused by the brake pad at the respective wheel end being pressed against the brake disk even though the braking request is not present. 
     
     
         9 . The method of  claim 6 , wherein the wheel speed sensors are arranged at the respective wheel ends such that fault-induced heating occurring at least at one of the brake pad and the brake disk results in a change in the sensor temperature of the associated temperature sensor of the associated wheel speed sensor. 
     
     
         10 . The method of  claim 6 , wherein at least one of the method is only carried out and the notification is only output when, within a specified time period before retrieving the first sensor temperature and the second sensor temperature, no braking request is present that has resulted in actuation of the particular service brake at the wheel end at which the sensor temperature concerned has been measured. 
     
     
         11 . The method of  claim 10 , wherein the time period is specified according to at least one influencing variable, which is selected from a group including:
 duration of the previous braking request, magnitude of the previous braking request, configuration of the particular service brake, position of the particular temperature sensor at the associated wheel end and/or inside the associated wheel speed sensor, ambient temperature, and vehicle speed.   
     
     
         12 . The method of  claim 1 , wherein each of the plurality of wheel ends has a bearing, wherein an axle shaft connected to the associated wheel is rotatably mounted at the wheel end via the bearing; the wheel speed sensor is arranged at the wheel end such that fault-induced heating occurring at the bearing of the associated wheel end results in a change in the sensor temperature of the associated temperature sensor of the associated wheel speed sensor. 
     
     
         13 . The method of  claim 11 , wherein the notification at least one of when the deviation limit value is exceeded and if the two sensor temperatures deviate too widely from each other includes that the bearing at the wheel end for which a higher sensor temperature has been ascertained is overheating or has overheated as a result of a fault. 
     
     
         14 . The method of  claim 13 , wherein the fault consists in the bearing being damaged. 
     
     
         15 . The method of  claim 1 , wherein the first wheel end and the second wheel end are located on a same vehicle axle of the vehicle or on different vehicle axles of the vehicle. 
     
     
         16 . The method of  claim 15 , wherein the temperature deviation is formed between a first mean value and a second mean value, wherein:
 the first mean value is formed from the first sensor temperature, which is measured at a first vehicle axle at the first wheel speed sensor by the first temperature sensor at the first wheel end, and from a further sensor temperature, which is likewise measured at the first vehicle axle at a further wheel speed sensor by a first further temperature sensor at a first further wheel end of the plurality of wheel ends; and,   the second mean value is formed from the second sensor temperature, which is measured at a second vehicle axle at the second wheel speed sensor by the second temperature sensor at the second wheel end, and from a second further sensor temperature, which is measured at the second vehicle axle at a further wheel speed sensor by a second further temperature sensor at a second of the plurality of wheel ends.   
     
     
         17 . The method of  claim 1 , wherein the vehicle is a commercial vehicle. 
     
     
         18 . An evaluation unit for a vehicle, the evaluation unit being configured to read from at least two wheel speed sensors, which are each arranged at different wheel ends of the vehicle and which each have a temperature sensor, a sensor temperature, which is measured in a sensing region, which encompasses at least the respective wheel speed sensor; the evaluation unit comprising:
 a processor;   a non-transitory computer readable medium having program code stored thereon;   an input;   an output;   the evaluation unit being configured to read, via said input, a first sensor temperature measured by a first temperature sensor of a first wheel speed sensor at a first wheel end and to read, via said input, a second sensor temperature measured by a second temperature sensor of a second wheel speed sensor at a second wheel end;   said program code being configured, when executed by said processor, to determine a temperature deviation on a basis of the first sensor temperature and the second sensor temperature;   said program code being further configured, when executed by said processor, to compare the temperature deviation with a deviation limit value; and   the evaluation unit being configured to output, via said output, a notification at least one of when the deviation limit value is exceeded and if the two sensor temperatures deviate too widely from each other, wherein the notification includes that a temperature change induced by a fault has been detected at least at one of the wheel ends that have a wheel speed sensor having a temperature sensor.   
     
     
         19 . A vehicle comprising:
 a plurality of wheel ends, wherein at each wheel end a wheel is mounted rotatably;   said plurality of wheel ends including a first wheel end having a first wheel speed sensor for measuring a wheel speed of the associated wheel and a second wheel end having a second wheel speed sensor for measuring a wheel speed of the associated wheel   said first wheel speed sensor having a first temperature sensor configured to measure, around a position of said first temperature sensor, and to output a first sensor temperature in a first sensing region, which encompasses at least said first wheel speed sensor;   said second wheel speed sensor having a second temperature sensor configured to measure, around a position of said second temperature sensor, and to output a second sensor temperature in a second sensing region, which encompasses at least said second wheel speed sensor;   an evaluation unit configured to:
 read the first sensor temperature measured by said first temperature sensor of said first wheel speed sensor at said first wheel end; 
 read the second sensor temperature measured by said second temperature sensor of said second wheel speed sensor at said second wheel end; 
 determine a temperature deviation on a basis of the first sensor temperature and the second sensor temperature; 
 compare the temperature deviation with a deviation limit value; and, 
 output a notification at least one of when the deviation limit value is exceeded and if the two sensor temperatures deviate too widely from each other, wherein the notification includes that a temperature change induced by a fault has been detected at least at one of said first wheel end and said second wheel end. 
   
     
     
         20 . The vehicle of  claim 19 , wherein said evaluation unit is a component part of a brake control unit of a braking system of the vehicle. 
     
     
         21 . The vehicle of  claim 19 , wherein the vehicle is a commercial vehicle. 
     
     
         22 . The vehicle of  claim 19 , wherein said wheel speed sensors are actively driven.